Abstract 10674: Determining the Risks of Magnetic Resonance Imaging at 1.5 Tesla for Patients with Pacemakers and Implantable Cardioverter Defibrillators (The MagnaSafe Registry)
Objective: The MagnaSafe Registry is a multicenter, prospective study designed to determine the frequency of major adverse clinical events and device parameter changes for 1500 patients with standard cardiac implantable electronic devices who undergo clinically-indicated, non-thoracic MRI at 1.5 tesla.
Methods: Device interrogation was performed pre- and post-MRI using a standardized protocol. Pacemaker-dependent subjects were programmed to an asynchronous pacing mode, and all non-dependent subjects had pacing functions deactivated. For implantable cardioverter defibrillator (ICD) patients, all therapies were programmed to off for those not pacing-dependent; pacing-dependent ICD subjects were excluded from the registry. Noninvasive monitoring was performed throughout the MRI. Primary study endpoints were device failure, generator/lead replacement, induced arrhythmia, loss of capture, electrical reset, or clinically-relevant device parameter changes.
Results: Between April 2009 and May 2011, 314 MRI studies involving 233 pacemakers and 81 ICDs were performed at 9 sites. Pacemaker dependence was noted in 21%. MRI duration was 38 ± 18 minutes, and MRI was performed 2.7 ± 2.0 years after generator implant. No deaths, device failures, generator/lead replacements, losses of capture, or ventricular arrhythmias occurred. One case of partial electrical reset was observed. Three episodes of self-terminating atrial fibrillation were noted (in each case the patient had a history of paroxysmal atrial fibrillation). There was a decrease in battery voltage of ≥0.04V in 5% of devices, a pacing lead impedance change of ≥50 Ω in 3%, and a high-voltage impedance change of ≥3 Ω in 19%. A decrease of ≥ 50% in P-wave and ≥ 25% in R-wave amplitude occurred in 0% and 3% of measurements, respectively. A pacing threshold increase of ≥ 0.5V at 0.4 ms occurred in 1% of leads. Seventeen percent of MRI studies resulted in at least one clinically-relevant device parameter change.
Conclusion: Preliminary results of the MagnaSafe Registry demonstrate no deaths, device failures, generator/lead replacements, or losses of capture after clinically-indicated non-thoracic MRI at 1.5 tesla. A low rate of clinically-relevant device parameter changes was noted.
- © 2011 by American Heart Association, Inc.